Will not hold zero - Pulsar Trail XP50 1.6-12.8x42mm Thermal Imaging Rifle Scope

I bought the xq 50 Trail and the xq 38 Helion. I like everything about the optics except for the Trail will not hold zero! I believe that temperature fluctuation is moving the innards of the scope. I contacted them and told them of my problem. They instructed me to sent the scope back to them. They sent me another xq50 Trail and I had the same problem with the replacement scope. They won't give me my money back. So now I am stuck with a useless thermal scope.
I live in ND. I am hunting typically in temperatures from zero to 40 degrees. I can zero this scope before I go hunting, and an hour of two later, can't hit the broadside of a coyote at 50 yds.
should have bit the bullet and bought a trijicon